Cross-wired organ system and rectifier therefor



Aug. 23, 1960 D. J. LESLIE 2,949,803

CROSS-WIRED ORGAN SYSTEM AND RECTIFIER THEREFOR Filed Feb. 25, 1957Eenom/ar G'ena-m'ar INVENTOR. flax A40 rl L551. /s,

J WMJ- United States Patent G Donald J. Leslie, 313 S. Fair Oaks Ave.,Pasadena 1, Calif.

Filed Feb. 25, 1957, Ser. No. 642,025 6 Claims. (Cl. 84-111) Thisinvention relates to an electric organ, and particularly to keyingsystems for purposes of obtaining various overtones, harmonics and thelike.

Electric organs contain a great quantity of equipment, there being asubstantial multiplication of similar equipment by virtue of the factthat there are numerous notes in the desired musical range. In addition,a plurality of manuals again multiplies the equipment required. The costof electric organs is, accordingly, quite high. The demand for electricorgans would increase very substantially if the price could bematerially reduced.

One object of this invention is to provide an electric organ havingquality features in a simple and inexpensive manner.

In order to obtain controlled harmonic-s, overtones, subtones and thelike, which are so necessary to create the desired musical effects, aplurality of generators is often provided for each key or note. It hasbeen proposed that fundamental tone generators alone be provided andthat the keys be appropriately cross-wired to operate generators fallingclose to the desired harmonic or overtone relationship. This, of course,seems to obviate a great deal of equipment. The only compromise seems tobe a slight difference in frequency between some true harmonics and thefrequency of the fundamental which approximates the harmonics, overtonesor the like. However, the relative amplitudes of the harmonics,overtones and the like cannot in a simple manner be controlled. If theoutput of the generators depends upon voltage applied, for example, theproblem is how to transmit different voltage in the cross-wire circuits.This can be done by using a plurality of bus bars and a plurality ofcontact arms for each key respectively engageable with corresponding busbars. Each bus bar corresponds to a particular fundamental or harmonic.Thus, the first, second and third bars may correspond to fundamental,second and third harmonics. Of course, more numerous bus bars areprovided in practice to achieve the numerous de sired frequencycomponent.

In this arrangement, the second contact arm for the C key, for example,is cross-wired to the generator for C Similarly, the second contact armsfor C 1 D etc. are cross-wired to the generators for C 1? and DDifferent voltages, preferably controlled in value, are applied to eachof the bus bars.

The difficulty with this arrangement may become clear on analysis. Thereare several connections made at each generator terminal, includingvarious. cross-wiring circuits as well as the main contact arm for thatgeneraton Since these connections are from different bus bar's, shortcircuit conditions exist unless the voltages at all of the bus bars areequal. But equal voltages are undesired since in this case impulseswould be produced in which all frequency components are equal inamplitude.

In order to provide different bus bar voltages for controlling relativeharmonic content and to overcome short circuit problems, aunidirectional conductor such as a rectifier can be inserted in everycross-wiring circuit. This solution is impractical since this meanshundreds of rectifiers, because there may be hundreds of cross-wiredconnections in a single instrument. However, this has been done sinceproviding numerous rectifiers may be more desirable than providingnumerous generators. Clearly a better type of amplitude control ofharmonics in a crosswired keying system is preferable.

A second solution seems possible. By inserting a rectitier in the supplylead to the bus bars, short circuit conditions can be avoided by the useof just a few rectifiers. However, this produces spurious results. Inthis instance, if, for example, keys for C and C are both depressed, thesecond harmonic bus bar will be supplied with full voltage, and otherkeys simultaneously operated will have second harmonic in full,unattenuated amplitude even though the corresponding key in octaverelationship is not operated.

It does not appear obvious that a solution exists.

The primary object of this invention is to provide a practical solutionto this problem in which only a slight amount of extra equipment isrequired and in which spurious operations are nevertheless avoided. Toaccomplish this purpose, the bus bars themselves incorporate novelrectifying means.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of oneembodiment of the invention. For this purpose, there is shown a form inthe drawings accompanying and forming part of the present specification.This form will now be described in detail, illustrating the generalprinciples of the invention; but it is to be understood that thisdetailed description is not tobe taken in a limiting sense, since thescope of this invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a diagrammatic view illustrating a system incorporating thepresent invention; and

Fig. 2 is an enlarged fragmentary longitudinal sectional view of one ofthe bus bars.

In Fig. 1 a series of electrical devices or tone generators 10, 11, 1213, 14 create electrical impulses corresponding to musical tones.

By way of example, the generator 10 generates impulses corresponding tomiddle C, designated conventionally as C The generators 11 and 12correspond to C 1? and D and the generators 13 and 14 correspond to Cand C 1; The generators 10 through 14 are, of course, representative ofa complete set of generators in an electric organ.

The generators may comprise vibrating reeds, electronic oscillators orother suitable devices. The neces sary characteristic, so far as thepresent invention is concerned, is that the amplitude of output by thegenerators may be determined by the amplitude of a supply voltage or thelike.

Keys 15, 16, 17, 1S and 19, arranged in usual keyboard fashion, operateappropriate control or energization circuits for the generators.Associated with the key 15, for example, is a contact arm 20 whichengages a bus bar 21 upon depression of the key 15. The bus bar 21 isconnected to a source of supply voltage through a lead 22. Upondepression of the key 15, the contact arm 26 transmits voltage to theeorrseponding generator 10 and an appropriate signal is created. Contactarms 23, 24, 25, 26, respectively associated with the keys 1 6, 17, 18,19, similarly cooperate with the bus bar 21 to energize or control theirrespective generators 11, 12, 13 and 14.

In order to provide overtones, subtones, harmonics and the like,additional contact arms, cooper-able with additional bus bars 27 and 28,are provided. For example, the first harmonic of C namely, C can beadded to the output whenever the C key 15 is depressed. This isaccomplished by a second contact arm 29 operated by the key 15. A lead30 connects this second arm 29 to the generator 13.

The second contact arm 29 engages the bus bar 27 to which is supplied anappropriate, controlled voltage different from that at the bus bar 21.In the present example, thebus bar 27 is at five volts, and the bus bar21 is at ten volts.

If the bus bar 27 is operative, depression of the key 15 will causeenergization or control of the generators 10 and 13. The voltage appliedfrom the bus bar 27 to the C generator 13 differs from that applied tothe C generator 10. Accordingly, the ratio of second harmonic tofundamental is controlled by appropriate choice of the voltage of thefirst and second bus bars.

Second contact arms 31, 32, respectively associated with the keys 16 and17 for Chi and D similarly cooperate with the second bus bar 27 and arecorrespondingly cross-wired to generators 3i and D 11 By inserting aswitch ahead of the second bus bar 27 or by physically moving the busbar27 away from operative position with respect to the second contact arms29, 31, 32, etc., the presence or entire absence of second harmonics dueto cross-wiring can be controlled by the musician. Furthermore, thevoltage applied to the second bus bar 27 can also be varied by apotential arrangement or the like. By such means, the desired intensityof the second harmonic relative to the fundamental may be controlled.

The third contact arms 33, 34 cooperate with the bus bar 28, and thesethird arms may be cross wired to generators for notes bearingappropriate overtone or subtone relationship with respect to the notesproduced by the main contacts of the respective switch sets.

As many bus bars may be provided as are desirable or necessary. As manyas eight or ten may be provided in order to control numerous harmonics,overtones and the like.

Should the keys 15 and 18- for C and C be simultaneously depressed, thesecond harmonic of C, will disappear as such, since the generator 13will be supplied with full voltage through the bus bar 21. Similarly,simultaneous depression of any two keys in which a cross-wiringrelationship exists will cause the crosswired circuit to besubordinated. This does not detract from esthetic effects.

If any cross-wired keys are simultaneously depressed, a possibility ofshort-circuiting exists. Thus, for example, if keys 15 and 18 for C andC are simultaneously depressed, the bus bar 21 connected to the ten-voltsource connects through the main contact arm 25, the cross-wiring 30,the second contact arm 29 of the key 15, through the bus bar 27 to thefive-volt source.

To prevent this short-circuiting relationship, each bus bar incorporatesa unidirectional conductor or rectifier structure. This is shown indetail in Fig. 2.

The bus bar 27, for example, incorporates a conductive base rod 35. Thebase rod 35 is coated with material 36 having unidirectional orrectification propersuch as selenium, germanium, silicon or the like.Contact islands 37, 38, 39 are supported upon the layer 36 and areprovided for cooperation with the second contact arms 29, 31, 32.

Of course, as many contact islands are provided as there are keyscooperating with the bus bar 27. Instead of a complete coating, therectifying layer can be provided as a strip only along one side of thebase rod. If convenient or desirable from a manufacturing standpoint, aseries of short strips or rings can be provided instead of a continuousstrip or coating. The shortcircuit condition can no longer arise. In theexample given above, the layer 36 blocks .the higher voltage at thecon-tact island 37 and prevents reverse current flow through the bus bar27.

The first or main bus bar 21 may also be provided with a rectifierstructure since in some cases, as in oboe tones for example, the secondharmonic exceeds the fundamental in amplitude.

The thickness of the layer and/or the material comprising the layer 36may be varied in accordance with the voltages required in the particularsystem. In a system utilizing transistor oscillators, the voltagesapplied to the generators normally do not exceed fifteen volts.Accordingly, a thin selenium layer may be provided to achieve effectiveoperation. Should higher voltages be present, such as in connection withpolarizing voltages for vibrating reeds, the layer may be made ofgermanium or other more effective rectifying material.

The bus bar can be readily provided with the rectifying layer 36. Byincorporating the rectifier structure in the bus bar, it is unnecessaryto provide separate rectifiers for each of the cross-wired circuits. Thelayer prevents application of an undesired high voltage to the base rod35, and spurious results are avoided.

The inventor claims:

1. For use in a cross-wired electric organ: an elongate. conductive busbar; a layer of material having rectification properties and extendingalong the length of the bar; and a plurality of electrically separatecontact means secured to the layer at spaced positions along the bar.

2. For use in a cross-wired electric organ: an elongate conductive busbar; material having rectification properties and located along thelength of the bar; and a plurality of electrically separate contactsselectively mov-, able to be placed in electrical contact with thematerial at spaced positions along the bar.

3. In an electric organ system of the class including: a plurality ofbus bars; a plurality of keys, each having a series of cont-act meansengageable with the respectivev bus bars; a plurality of impulseproducing means operable upon engagement of the contact means with saidbars; means for cross-wiring the contact means for adding harmonies orthe like to impulses upon depression of the keys; means for applyingvoltages in controlled amounts to the bus bars; the combinationtherewith of: means located along each bus bar and interposed betweenthe bus bar and the corresponding contact means for preventingshort-circuiting conditions upon the simultaneous operation ofcross-wired contact means.

4. For use in an electric organ or the like: an elongate conductivemember; a plurality of independently operable electrically separatecontact means selectively engageable with the member; and rectifiermeans. interposed between each of the contact means and the member.

5. For use in an electric organ or the like: an elongate conductivemember; a plurality of independently operable electrically separatecontact means selectively engageable with the member; and rectifiermeans carried by the member and interposed between each of the contactmeans and the member.

6. In an electrical switching system utilizing a plu rality of bus barsadapted to be connected to sources of electrical energy, said systemhaving a plurality of circuit controllers, and a plurality of electricaldevices adapted to be connected to selected bus bars by the aid of saidcircuit controllers, at least some of the circuit controllers cooperablewith dilferent bus bars being connected to a common device, thecombination therewith of rectifier material carried by the bus bars andinterposed between the circuit controllers and the bus bars forpreventing cross-Wiring short circuits between the bus bars by way ofthe circuit controllers.

References Cited in the file of this patent UNITED STATES PATENTS2,504,906 Tremblay Apr. 18, 1950 2,528,086 Schenck Oct. 31, 19502,562,471 Martenot July 31, 1951 2,579,358 Bourn Dec. 18, 1951'2,767,264 Scott Oct. 16, 1956 2,832,898 Camp Apr. 29, 1958 2,852,973Corbett Sept. 23, 1958;

